2C-I was first synthesized and investigated for human activity by Alexander Shulgin in 1976[2] and later described in his 1991 book PiHKAL ("Phenethylamines I Have Known and Loved").
Its PiHKAL entry notes it for being "very colorful and active" but without "feelings of insight, revelation, or progress toward the true meaning of the universe."[3]

2C-I is sometimes confused for the analog 25I-NBOMe (an abbreviated form of 2C-I-NBOMe). It is commonly sold in its hydrochloride salt form, which is a fluffy, sparkling, white powder that is sometimes pressed into tablets for distribution on the street. It first briefly gained some popularity in the late 1990s and early 2000s, where it was sold in several smart shops as a replacement for 2C-B following its scheduling in 1995.[4] It also has a history of being sold online as a research chemical before becoming scheduled.

Limited data exists about the pharmacological properties, metabolism, and toxicity of 2C-I, and it has a limited history of human use. It is highly advised to use harm reduction practices if using this substance.

Chemistry

Generic structure of a phenethylamine molecule

2C-I, or 2,5-dimethoxy-4-iodophenethylamine, is a substituted phenethylamine comprising a phenyl ring bound to an amino (NH2) group through an ethyl chain. 2C-I contains methoxy functional groups CH3O- attached to carbons R2 and R5 as well as an iodine atom attached to carbon R4 of the phenyl ring. 2C-I belongs to the 2C family of phenethylamines which contain methoxy groups on the 2 and 5 positions of the benzene ring.[5]

Subjective effects

The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWikicontributors. These effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.

Physical effects

Stimulation - In terms of its effects on the physical energy levels of the user, 2C-I is usually considered to be very energetic and stimulating in a fashion that is quite comparable to MDMA, although it is 'encouraged' instead of 'forced'.

Spontaneous physical sensations - The "body high" of 2C-I is manifested as one of the most proportionally intense in comparison to almost all of the classical psychedelics. The sensation itself can be described as an intense and slightly uncomfortable energetic pins and needles sensation that constantly encompasses a person’s entire body. It is usually felt over every square inch of the skin but occasionally manifests itself in the form of a continuously shifting, tingling sensation that travels up and down the body in spontaneous waves. Alongside this, many users commonly report that the "body high" can be particularly uncomfortable and sometimes accompanied by dysphoric aches and urges to shift the position of one's body and prolonged tensing of unusual combinations of muscle groups.

Physical euphoria - Feelings of frequent but unpredictable rushes of warm physical euphoria are extremely common. These can move from the top of the head downwards before enveloping one's whole body.

Visual effects

Enhancements

Distortions

Drifting(melting, flowing, breathing and morphing) - In comparison to other psychedelics, this effect can be described as simplistic and bland in detail, slow and smooth but sometimes jittery in motion, static in appearance and unrealistic/cartoon-like in style.

The visual geometry that is present throughout this trip can be described as more similar in appearance to that of LSD or 2C-B than that of 2C-E, psilocin, or ayahuasca although it is much blander and less detailed. They can be comprehensively described as unstructured in their organization, algorithmic in geometric style, intricate in complexity, large in size, fast and smooth in motion, colorful in scheme, glossy in color, both soft and sharp in their edges as well as equally rounded and angular in their corners. They seem high in algorithmic visuals such as fractals and at higher doses are significantly more likely to result in states of level 8A visual geometry over level 8B.

Hallucinatory states

Like LSD, while 2C-I is capable of producing a full range of low and high level hallucinatory states, this is extremely rare and inconsistent at higher levels but common at lower ones.

Cognitive effects

The head space of 2C-I is described by many as one which is relatively normal in its thought processes even at moderate to high doses. It is often said to lack insight when compared to that of 2C-E, psilocin and LSD.

Empathy, affection, and sociability enhancement - This component is consistently manifested only in the context of social settings in which one is within the company of others. These feelings of sociability, affection and empathy are a little weaker and less sharp than those found on substances such as MDMA and 2C-B but still prove strong enough to provide long-lasting therapeutic effects.

Auditory effects

Multi-sensory effects

Synaesthesia - In its fullest manifestation, this is a very rare and non-reproducible effect. Increasing the dosage can increase the likelihood of this occurring, but seems to only be a prominent part of the experience among those who are already predisposed to synaesthetic states.

Toxicity and harm potential

The toxicity and long-term health effects of recreational 2C-I use do not seem to have been studied in any scientific context and the exact toxic dose is unknown. This is because 2C-I is a research chemical with very little history of human usage.

Anecdotal reports from those who have tried 2C-I suggests that there are no negative health effects attributed to simply trying the substance by itself at low to moderate doses and using it very sparingly (but nothing can be completely guaranteed). Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

Tolerance and addiction potential

Although no formal studies have been conducted, it is not unreasonable to assume that as is the case with psychedelics in general, 2C-I is not habit-forming and that the desire to use it can actually decrease with use.

Tolerance to the effects of 2C-I are built almost immediately after ingestion. After that, it takes about 3-5 days for the tolerance to be reduced to half and 7-10 days to be back at baseline (in the absence of further consumption). 2C-I presents cross-tolerance with all psychedelics, meaning that after the consumption of 2C-I all psychedelics will have a reduced effect.

Dangerous interactions

Although many psychoactive substances are safe to use on their own, they can quickly become dangerous or even life-threatening when combined with other substances. The following lists some known dangerous combinations, but may not include all of them. A combination that appears to be safe in low doses can still increase the risk of injury or death. Independent research should always be conducted to ensure that a combination of two or more substances is safe to consume. Some interactions listed have been sourced from Tripsit.

Tramadol - Tramadol lowers the seizure threshold[6] and psychedelics may act as triggers for seizures, particularly in those who are predisposed to them.[citation needed]

Stimulants - Stimulants affect many parts of the brain. Combined with psychedelics, stimulation can turn into uncontrollable anxiety, panic, thought loops and paranoia. This interaction may cause elevated risk of psychosis.[citation needed]

Lithium - Lithium is often used as treatment for bipolar disorder. It may possibly cause elevated risk of seizures and psychosis due to its glutaminergic and GABAergic effects.[citation needed]

Legal status

Austria: 2C-I is illegal to possess, produce and sell under the SMG. (Suchtmittelgesetz Österreich)

Brazil - Possession, production and sale is illegal as it is listed on Portaria SVS/MS nº 344.[7]